Motor Control Systems – Bode Plot & Stability


Set point feedback controller

What is a control system? A control system alters the future state of its system to a more desirable outcome. We often work with feedback control systems (also called closed-loop control), where the result of the command is fed back into the control system. In particular we are looking for the error between the command […]

Fuse Locations, Protection, Shunt Regulation, & Motors


shunt regulator

Hi all I wanted to write a quick post today about where to place fuses and how to protect your robot. When you design a system it is often tempting to place a fuse on every component. This idea is fine for most batteries, sensors, and computers. However this can really cause destruction when you […]

Controlling Brushless DC motor with no Encoders


hall detection

This is just a quick post on controlling DC brushless motors with no encoders. This post applies to brushless motors that typically use hall sensors for commutation. This post does not apply to the hall-less ESC (electronic speed control) motors that typically run at very high speeds and are used for things such as quadcopters […]

Motors: Active, Reactive, and Apparent Power


power beer analogy

There are a bunch of confusing powers involved when we look at motors, especially with DC brushless motors. When your boss comes and asks you to measure the electrical power that your motor is using, it is often not straight forward. Typically the easiest way to get the current used by a motor is to […]

Copley Motor Controller Review


Copley controller

Hi all This is a post about the Copley Controls motor controllers. For this review I will be using a ACJ-055-09 (55Vmax and 9Apeak) motor controller (I love when product names mean something useful) with a 3 phase DC brushless motor. This is a good controller for distributed motion control. Copley makes several versions of […]

PID Control (with code), Verification, and Scheduling


PID equations

Hi all PID controllers are the workhorse of the controls world. PID controllers have the goal of taking some error in your system and reducing it to 0. While there are many other control strategies out there PID is probably the most common (unless you count human control) outside of just setting a setpoint. There […]

Selecting and Sizing Your Motor (and gear boxes)


motor planetary and harmonic gears

Hi all Selecting a motor is a critical task when designing a robot. In a prior post we discussed the different types of motors and feedback options as well as how to control those motors. In this post we will focus on how to size your motor and select the proper gearing. In the main […]

CAN bus (CANopen & CiA) for Motor Control


CAN topology

A Controller Area Network, or CAN for short is a common message based protocol used in cars and other vehicles. If you are trying to interface with a car/truck/bulldozer, there is a good chance that you will be reading data its CAN bus, and sending it commands via its CAN bus. It is also used […]

Motor Controllers & Amplifiers


motor architectures

Hi all I recently wrote a post on different types of motors and feedback options, now I want to talk about how to control those motors. Each motor is often refereed to an “axis”, so a 8 axis motor controller can control up to 8 motors. There are two different components used in the control […]

Motors and Feedback (encoders)


brushless motor

Hi all There are many types of motors and feedback methods to choose from. Which do you need? Keep reading to find out more about selecting your motor stackup. Since most field robots are DC powered I am skipping the many types of AC motors that are out there. In addition to this post you […]